In “Salt, Silver & Sun,” PhoPa Gallery takes a snapshot of photography before the age of pixels and Pinterest. The exhibit features images by 16 contemporary Maine artists using 19th-century photographic methods, such as daguerreotype, anthotype and collodion. The show, including Michael Kolster’s 2014 ambrotype image, “Lisbon Trees,” is on view to April 18 at PhoPa, 132 Washington Ave., Portland. Gallery hours are noon to 5 p.m., Wednesday to Saturday.